What is in a name?
Faeces, excrement, dung or shit is what it is. It makes our world and there is no point in naming or shaming it but accept it as fundamentally important to life. Scientists have created a museum of poop at the Isle of Wight Zoo in the UK. It allows zoo-goers to get up close and personal with 20 individually encapsulated stools. The poos come from various animals: there are samples from the zoo’s lions, as well as from meerkats, skunks – there’s even human baby poo.
The museum’s curator Nigel George says even a layperson can tell a lot about an animal by examining a sample of its faeces.
Crow poo, for instance, generally contains quite a lot of bones or beetle wing cases in it. “The carnivore poos tend to be a lot smellier than the herbivore ones,” he adds. Cow poo is 80% water and comes out in large, sloppy dollops, whereas kangaroo poo is generally more like little, firm pellets.
One herring gull bird sample had remnants of plastic in it, showing how there is now a human impact on animal poo.
With an average poo containing about 75% water, the team have learnt by trial and error how to encapsulate the turds to “make them less smelly and safe for the public to look at”.
Whale poop makes the world’s nutrients go round.
While most marine animals eat close to the water’s surface and poo in the deeper waters, whales do the opposite. It’s this, Joe Roman says, that makes all the difference.
“When whales come up to the surface, right before their last dive, they do a big dump,” says Roman, a biologist at the University of Vermont, US.
This faecal plume, as it’s known, is rich in nutrients, depositing vast quantities of nitrogen, iron and phosphorus at the water’s surface.
“So they can fertilise the ocean,” says Roman. “[They] bring the nutrients back to the surface.”
The effect is known as the whale pump – and it’s something that Roman has spent the past 10 years studying.
Once the nutrients are at the water’s surface, fish such as salmon can consume them. These fish are then in turn eaten by seabirds who transport the nutrients from the sea to their breeding colonies onshore, where they are subsequently eaten by land animals such as bears. In this sense, Roman says “whales play a part in bringing [the world’s nutrients] from the bottom of the ecosystem to land”.
Until about 60 million years ago, there were no whales. It was around that time that one group of land mammals began dipping their toes into rivers, eventually becoming fully aquatic and colonising the ocean as whales and dolphins. The whales started feeding on fish and crustaceans and so evolved the ability to break down chitin – a component of the hard shell or exoskeleton that surrounds some shellfish.
“Most mammals can’t break this down. It’s meant that the microbial community of whales is completely different from what we realised,” he says.
The makeup of whale faeces depends a lot on the individual whale responsible, and its diet, says Roman. If the whale feeds on krill, its poo tends to be in the form of red or pink logs about the size of a fist. But if they’re feeding on fish, it’s diffuse and a dark green, about the size of a research vessel, he says.
“It’s an immediate injection of nutrients. Both have the same impact but in different ways.”
Let us look at dung beetles. “… (They) are living on the last bit of nutrients that the original eater couldn’t get out of the food,” says Marcus Byrne of Witwatersrand University in Johannesburg, South Africa. “It’s really the knife edge.”
Despite having a brain the size of a grain of rice, dung beetles have some pretty impressive talents, says Byrne, They mould the poo they harvest into spherical balls and then roll it away from the competition.
He says the way they procreate and fight over mates is remarkably developed given their small size. Males advertise their fitness through massive horns on their heads, he says. “They’re tiny animals but they fight for females like they’re antelope, deer or caribou.”
The small males of the species have also evolved to have larger testes than the bigger beetles.
Apart from being sexual stallions and impressive poo-ball rollers, what really sets them apart is their navigation skills. “They look at the sky and use signals to orientate and navigate themselves,” says Byrne. While we humans are map navigators, the beetles can perceive things we can’t see such as polarised light, colour gradient and intensity gradient.
Byrne showed that one species even uses the Milky Way as a celestial compass to orientate itself, allowing the beetles to shift their poo balls by night.
“It’s romantic and impressive. There’s this stupid little animal that’s basically looking at the edge of our galaxy,” he says.
Poo has now come into the field of archaeology as well.
Hannibal is generally considered one of the greatest military commanders in history. He was the leader of the North African Carthaginian army during a war with Rome, which lasted from 218 to 201BC. Where Hannibal crossed the Alps with his army and 15,000 horses (and several war elephants) – has remained an enigma. Some have suggested this crossing from modern-day France into Italy was at a pass called the Col de Traversette, 3000m above sea level. “There was a lot of circumstantial evidence that this was the route but no one has ever come up with something that’s scientific evidence in that it can be tested,” says Chris Allen, an environmental microbiologist at Queen’s University, Belfast, UK.
The mystery has been debated for the past two millennia by historians, statesmen, academics and even by Napoleon. It might soon be solved thanks to a whole heap of ancient horse droppings.
“If you’ve got 15,000 to 20,000 horses in the one place for two days, you know you’re going to have some sort of residue,” says Allen.
Partnering with archaeologists, Allen and his team found a hole the size of a football pitch not far from the Col de Traversette. Using genetic analysis and environmental chemistry, the team managed to unearth a mass deposition of animal faeces.
They took soil samples at 5cm intervals to a depth of 70cm, which took them through soil horizons that would have formed 2,200 years ago during Hannibal’s life.
“This churned up layer shows something very physical and distinct happened about 2,180 years ago,” he says. “It suddenly becomes very physically disturbed.” The disturbed layer was rich in ancient horse dung, which the team could carbon date to about 200BC – very close to 218BC, which is when Hannibal is thought to have crossed the Alps. The soil sample was also really high in Clostridia bacteria, a microbe commonly found in the stools of horses.
“Twelve percent of soil samples had this Clostridia and its bang on the dates that it’s expected. There is a six-fold increase at the correct date,” says Allen, equating the findings to a ‘genetic time capsule’. These observations, along with a number of others, create a “fairly convincing story that 2,200 years ago a very large number of mammals went through this place and they left something behind”.
All things must come to an end. Pass the toilet roll, please.
(Ack: BBC/earth-Katie Silver of July 12, 2016)
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